I just called USCIS 1-800 number and ask them the following questions:
Q: I am now in H1B, filed change of employer. Can I start working for new employer before I get approval notice?
A: As far as your previous H1 visa is valid. You can start working for new employer.
Q: If my H1 transfer gets denied, but I have already start working for new employer. What can I do? Did I violate any immigration law or work illegally.
A: Your new employer can refile or appeal. You didn't violate any immigration law as far as your previous H1 visa is valid.
It looks like there are some inconsistency based on the information I get from this forum regarding transfer denied and illegal working. Can anybody clear this? When they talk about previous H1 visa is valid. Does it mean my previous employer didn't withdraw my H1B or my H1B does not expire?
Thanks.